Silver halide photographic element containing a polyanionic color former and a gelatin antiabrasion layer



United States Patent 3,361,565 SILVER HALIDE PHOTOGRAPHIC ELEMENT CON-TAINING A POLYANIONIC COLOR FORMER AND A GELATIN ANTIABRASION LAYERJacob Quentin Umberger, Holmdel, N.J., assignor to E. I. du Pout deNemours and Company, Wilmington, Del., a corporation of Delaware NoDrawing. Filed Ian. 21, 1964, Ser. No. 339,112 11 Claims. (Cl. 96-74)ABSTRACT OF THE DISCLOSURE A multicolor photographic element having (1)differentially sensitized silver halide emulsion layers containing colorformers one of which is a polyanionic color former, the layers having anintegral thickness, 6, of not more than 12.5 microns and (2) a gelatinantiabrasion layer containing an organic plasticizer having an O atomdoubly bonded to C, P or S and free from H atoms more acidic than pK=19, a boiling point above 200 C., a melting point below 40 C. andsoluble in water to at least 0.5 g. per liter.

This invention relates to color photography and more particularly tomulticolor elements for chromogenic development.

Multilayer color films containing polymeric colorformers have beenproposed and these have been found to yield the thinnest emulsion layersof any integral coupler system. Such multilayer color films aredisclosed in assignees copending application of Chu et al., Ser. No.113,100, filed May 29, 1961, now US. Patent 3,211,552. Such films,however, have suffered from brittleness of the color-forming layers indry atmospheres or climates. In addition to the ionizable groups,another contributor to this brittleness is the amide linkage, CONH, bywhich the coupler group is attached, directly or indirectly, to thepolymer backbone. Normally, atmospheric moisture or water molecules arebelieved adsorbed to such polar sites but, in dry atmospheres, loss ofadsorbed water frees these sites to set up a 3-dimensional network ofintermolecular hydrogen bonds which prevents the free rotation aroundchemical bonds necessary for plastic flexing and bending.

An object of this invention is to provide improved multilayer elementsfor chromogenic development. Another object is to provide multilayercolor films for chromogenic development which have both high resolvingpower values and the processing simplicity of integral coupleremulsions. A more specific object is to provide such films havingimproved flexibility, especially at low relative humidities. Yet anotherobject is to provide a simpler means of adding plasticizing materialswithout causing coating and sensitometric defects and without requiringthe use of special equipment. Still further objects will be apparentfrom the following:

The improved multicolor elements of this invention comprise a supportbearing 1) a plurality [preferably three] of differentially sensitizedsilver halide emulsion layers, each adapted to record images from lightin a different region (e.g., primary color region) of the visible3,361,565 Patented Jan. 2, was

spectrum and containing a color former having at least one nucleuscapable of forming a dye selected from the group consisting ofquinoneirnine, azomethine and azo dyes upon color coupling developmentof the exposed element, and gelatin or a mixture of gelatin and anotherpolymeric binding agent (e.g., a vinyl addition polymer) for the silverhalide crystals, and coated over said plurality of emulsion layers (2) agelatin antiabrasion layer containing an organic plasticizer having anoxygen atom in the molecule which is doubly bonded to carbon, phosphorusor sulfur, and being free from hydrogen atoms more acidic than pK,,-=l9and having (a) a boiling point above 200 C., (b) a melting point below40 C., and (c) a solubility in water of at least 0.5 and preferably morethan 3.0 g. per liter at 25 C. The binding agent and color former can bethe same, i.e., a polymeric color former, preferably polyionic. Thesupport preferably does not absorb the plasticizer. Preferred supportsembody meltcast, oriented polyester, e.g., polyethylene terephthalateand polycarbonate films.

Preferably, the gelatin antiabrasion layer will also comprise acolloidal dispersion of a low-melting, noniouized, water-insoluble,synthetic, vinyl addition polymer, preferably an acrylic acid ormethacrylic acid methyl or ethyl ester, in the form of a soft gel-likesolid at room temperature. Other auxiliary layers (i.e., antihalation,separator and filter layers) may also contain a plasticizer and/or acolloid dispersion of vinyl addition polymer as defined above. Thepolymer, which may be in the plasticized state, should have a secondorder transition temperature (glass transition temperature) of 0 C. orbelow.

In exemplification of the invention, a hydrophobic film support, e.g.cellulose acetate, cellulose triacetate, cellulose propionate, cellulosebutyrate, cellulose acetatebutyrate, etc., or a superpolymer such asnylon, polyvinyl chloride, polyester, e.g., polyethylene terephthalate,polycarbonate, etc., glass, wood, paper, etc., suitably subbed toprovide proper adhesion with layers to be coated thereon, is coated onone surface with an antihalation layer comprising gelatin in which thereis dispersed colloidal silver capable of absorbing light of all visiblewave lengths. Coated in order on the antihalation layer are agelatino-silver halide emulsion layer sensitive to blue and red lightand containing a polyanionic cyan color-former, a gelatin separatorlayer, a gelatino-silver halide emulsion layer sensitive to blue andgreen light and containing a polyanionic magenta color-former, a gelatinlayer containing a blue light-absorbing material, e.g yellow colloidalsilver, a gelatino-silver halide emulsion layer sensitive to blue lightand containing a polyanionic yellow color-former. Finally, there iscoated an antiabrasion layer from an aqueous coating solution comprisinggelatin, a plasticizer as described above, e.g. triethyl phosphate, acolloidal dispersion of a vinyl polymer (polyethyl acrylate), a gelatinhardening agent such as chrome alum and a non-ionic surfactant. Theantiabrasion coating solution contain 2% by weight gelatin, 3% by weightplasticizer and 2% by weight vinyl polymer.

In the above-mentioned Chu et al. application, there are discoloredcolor-formers, emulsion formulations, coated elements and processingprocedures suitable for use in this invention with the exception thatthe simple gelatin antiabrasion layer of that reference is to bereplaced with an antiabrasion layer comprising the high boilingplasticizer and, optionally, the dispersion of a vinyl polymer asdescribed above. A dispersion of a vinyl polymer may also be added tothe silver halide layers and/or one or more of the non-photosensitivelayers e.g., the antihalation layer as disclosed in assignees copendingapplication, Firestine and Stevenson, U.S. Ser. No. 183,759, filed Mar.30, 1962, abandoned Jan. 17, 1965.

The light-sensitive emulsion layers may be arranged with respect to thesupport in other manners and with other arrangements of spectralsensitivities and colorformers as is known in the art. Suitable otherlayer arrangements are disclosed in US. Patents 2,397,864, 2,927,019,2,927,024, and U5. 2,997,338. However, the advantages of the thinemulsion layers of this invention will be most appreciated in aconfiguration in which the uppermost light-sensitive layer contains ayellow colorformer.

Suitable plasticizers are disclosed in an article by Alan S. Haisser inModern Plastics Encyclopedia, 1963 Issue, vol. 40, No. 1A (September1962), pages 456-457, fol- .lowed (pages 460-478) by a PlasticizersChart. Any

of the plasticizers listed in this chart and conforming to the abovecharacteristicsthigh boiling point, water-soluble, containing adoubly-bonded oxygen, etc.) are suitable. for inclusion in thecompositions and elements of this invention. Other suitable plasticizershaving the prescribed characteristics are disclosed in the bookPlasticizers by D. N. Buttrey, 2nd edition, 1957, Cleaver- Hume Press,Ltd., London. Since the'antiabrasion over- .coating should contain asufiicient quantity of a watersoluble plasticizer to diffuse throughoutall layers of the film element, the plasticizer should have at least theminimum solubility specified. Thus many common plasticizers which have asolubility of less than 0.5 g./liter would be unsatisfactory in thisinvention, e.g. tricresyl phosphate, dimethyl sebacate, dioctylphthalate, triethylene glycol di-2-ethylhexoate and ethyl phthalyl ethylglycolate.

Other compounds, normally referred to as plasticizers, e.g. glycerine,diethylene glycol and triethylene glycol, should more properly beconsidered as humectants. These compounds do not themselves act stronglyas plasticizers but they absorb water from the air and it is thisabsorbed water which acts as a plasticizer.,0bviously, such compoundsare ineffective in fiexibilizing films if there is little or no water inthe air, i.e. under conditions of low relative humidity. Furthermore, ithas been found that these humectants cause problems such as pooremulsion aging stability under storage at high relative humidity. Thesecompounds do not contain the required doublybonded oxygen atom of thepresent invention.

The preferred vinyl polymer to be added as a dispersion to thephotographic emulsions is polyethyl acrylate. Its preparation usingdisodium-N-tallow-B-iminodipropionate as a dispersing agent, isdescribed in Procedure A of assignees copending application, Nottorf,Ser. No. 94,989, filed Mar. 13, 1961 (US. Patent 3,142,568, July 28,1964). In that same application there are disclosed a number of othersuitable vinyl polymers, dispersed with various amphoteric dispersingagents. Although a wide variety of polymeric vinyl compounds are useful,the preferred compound is an acrylic acid methyl or ethyl ester takenfrom the group consisting of a homopolymer of an acrylic acid ester, ahomopolymer of an a-hydrocarbon substituted acrylic acid ester and acopolymer of said acrylic acid esters, said copolymer containing atleast 90% by weight of units of said acrylic acid esters. In general,the ionic dispersing agents are preferred for use in preparing thepolymeric dispersions since they tend to form more stable dispersionsthan the nonionic agents. These preferred ionic dispersing agents inaddition to the above-disclosed amphoteric agents, also include anionicdispersing agents such as disclosed 4 a as being useful in preparingvinyl polymer dispersions in assignees Nottorf application, Ser. No.134,109, filed Aug. 28, 1961, now US. Patent 3,325,286, i.e. an ionicdispersing agent represented by the formula:

carbon atoms, e.g. 8 to 18 carbon atoms, and an organic radical of theformula IU-O-(O 01120132 wherein R is a branched chain alkyl radical ofat least 4 carbon atoms, e.g. 4 to 12 carbon atoms, and n is a number of1 to 12 and B is a radical selected from the group consisting of O -SO Mand -O CO M where M is a cation selected from the group consisting ofammonium and an alkali or alkaline earth metal, e.g., lithium, sodium,potassium, rubidium and cesium, and m is 0 or 1.

Cationic dispersing agents are useful but less preferred because theymay have a tendency to react with anionic color-formers. Also useful,but less preferred, are the nonionic dispersing agents since they mayform somewhat less stable dispersions. Mixtures of any of theabove-discussed dispersing agents may be particularly useful undercertain circumstances. Whatever dispersing agent is employed, it

is desirable that the dispersion be prepared in such a mannet that theaverage particle Size does not exceed one micron, e.g., according to theprocedures described in either of the above Nottorf applications.

In the above Chu et al. application, there is considerable emphasis onthe importance of thinness of the emul- V sion layers in order toachieve superior results in terms of resolution, definition, etc. Asdisclosed in that application, it is desired that the integral emulsionthickness (6) not exceed 12.5 microns, preferably 7.6 to 12.5 microns,and that the effective color-forming equivalent weigh of the binder notexceed 1750, preferably 500-1750. The thickness value, 6, was originallydefined in an article by I. Eggert and W. Grossman, The Resolving Powerof Three- Layer Color-Films, Naturwissenchaften 39, No. 6, 132- 133(1952), as the distance from the surface of the outermost photosensitivelayer to one-third into the innermost photosensitive layer. Theeffective color-forming equivalent weight is defined in detail in theabove Chu et al. ap-' plication but, briefly, is a measure of theefficiency of the total binder-color-former system in yielding thincolor emulsion layers, defined as the quotient obtained whencolor-former equivalent weight is divided by the fraction of the totalbinder comprised of color-former. In the present invention, it isdesirable to maintain the above ranges of thickness (6) and effectiveequivalent weight, even with the addition of plasticizers and vinylpolymer dispersions. It is significant to note that the addition oflatex plus plasticizer to the abrasion and/ or non-halation layers doesnot increase the value of 5 appreciably.

The novel elements of this invention are particularly applicable tonegative and reversal color films Whichare designed for exposure in acamera. In the case of color reversal films, the blue-sensitive layershould be outermost, and the remaining silver halide layers adapted torecord in the red and green regions of the spectrum being disposed inany order and preferablyall on the same side of the support. Thecolor-formers in the blue, green and red regions of the spectrum, ingeneral, should yield dyes upon development complementary incolor to theutilized sensitivity of the respective silver halide emulsion layers.

The invention will be further illustrated, but is: not ill? tended to belimited to the following examples.

Example I Polyethylene terephthalate film 0.0045 inch in thicknesshaving a vinylidene chloride copolymer l'ay'er'on one sur- 7 5 face, asdescribed in Example IV of U.S. 2,779,684, was provided with a thingelatin layer serving as a second substratum. This film base was thencoated with aqueous dispersions as described in Table A in the ordershown to form a color reversal film with the yellow emulsion outermost.

This G-layered film was now over-coated in separate sections withvarious antiabrasion layers comprising wator/ethanol (90/ 10 by volume)solutions of gelatin in 2% by weight concentration and the followingplasticizers in 3% by volume concentration: (a) triethyl phosphate, (b)triethyl citrate, (c) glyceryl triacetate, (d) bis-(methoxyethyl)adipate. A control coating was also made without of the flexibilizingmaterials added to the experimental films produced any photographicallydeleterious effects.

Example II A six-layered color film was prepared which was identicalwith Example I except the support was cellulose triacetate of 0.0052inch thickness having a thin gelatin anchoring substratum. Over separatesections of this film were coated antiabrasion layers similar to ExampleI in gelatin, hardener, and surfactant content and containing 3 parts ofvarious high-boiling organic liquids per 2 parts of gelatin by weight.The films were tested at room tem- TABLE A Color Colloidal Gelatin PEA 1Former Silver mgJdm. mg./dm. mgJdm. mgJdm.

Antihalation layer 11. 1 3. 7 3. 4 Cyan layer 2 11. 10. 5 7 6 Separatorlayer. 18. 0 1. 5 Magenta layer 12.9 5 7 6 0 Yellow filter layer 10. 0l. 5 Yellow layer 4 5. 7 6 2 17. 3

1 Polyethyl acrylate (dry weight) obtained from the aqueous dispersiondescribed in Examp e 1 The cyan color-former is a 1:1 copolymer of Hiydroxy-N-(beta-vinyl-oxyethyl) -2-naphthamide and maleic anhydride asdescribed in Example I of assignees copending application of Umberger,Ser. N 0. 113,101, filed May 29, 1961, refiled as continuation-impartapplication Ser. No. 419,227, Dec. 17, 1964 (U.S.P. 3.299,013, Jan. 17,1967).

a The magenta color-former is a 1/1.25/0.75 copolymer of1-phenyl-3'methaorylamido-5- pyrazolonelacrylic acid/acrylamide asdescribed in Example V of assignees copending application, Firestine andUmberger, Ser. N 0. 21,959, filed Apr. 13, 1960 (U.S.P. 3,163,625,

Dec. 29, 1964) 4 The yellow color-former is a polyanioubenzoylacetanilide prepared by transacetalization of 100 parts of lowviscosity 99% hydrolyzed polyvinyl alcohol with 120 parts of a-benzoylacetamidobenzaldehyde ethylene glycol acetal and 50 parts ofo-suliobenzaldehyde in an ethanol-water reaction medium withp-toluenesulfonlc acid to pH 1.7 as acetalization catalyst to yield acolor-former of 775 equivalent Weight.

plasticizer, i.e., from 2% gelatin solution only. Chrome alum andnon-ionic surfactants, e.g., saponin, were also present in these coatingcompositions. The temperatures of the solutions were 95-100 F. atcoating and the coating speed adjusted so as to obtain a coating wgt. ofdry gelatin of about 10 to mg./dm.

After drying and seasoning under ordinary room conditions for severalweeks the coatings were subjected to the wedge-brittleness testdescribed by P. Z. Adelstein in Journal of Photographic Science andEngineering, vol. 1, No. 2, October 1957, pages 63-68, in a room held at10% relative humidity (RH). Also measured was the curl expressed indiopters, viz., the reciprocal of the radius of curvature measured inmeters.

TABLE B Coating Emulsion Crack Curl Diopters Identification Diameter,inches perature as in Example I and the following results were obtained:

TABLE C pl ti i Emulsion crack diameter 0% RH, inches Triethyl phosphate0.29 Propylene carbonate 0.31 N,N-dimethylcaproamide 0.39 Bis(Z-methoxyethyl) adipate 0.33 Dimethyl phthalate 0.35 Triacetin 0.35Control (gel only) 0.40

A few of the films of the above set were again tested at 10% relativehumidity but at 225 F. temperature compared with the previous roomtemperature tests.

TABLE D Plasticizer: gl f igff 3352* F., inches Triethyl phosphate 0.52

Triacetin 0.53

Control (gel only) 0.64

Example III A six-layered color film like that of Example II was made.However, the alcohol content of the antiabrasion layer coatingcomposition was increased in order to dissolve plasticizers of lowerwater solubility than in the previous examples. In preparing theantiabrasion coating compositions, 15 parts by volume of theplasticizers were dissolved in 150 parts by volume ethanol and addedslowly with stirring to 200 parts by volume of 4.5% aqueous gelatinsolution (at 125 F.) containing the usual hardener and surfactants. Thecoating temperature was F. and coating speed 10 ft./min. From thefollowing table, recording film testing as in Example I, it will be seenthat some very water soluble materials, e.g., triethyl phosphate, havebeen included withless water-soluble plasticizers.

TABLE E Emulsion Plasticizer Crack Diam- Curl star at Diopters at RH,inches 10% RH Triethyl phosphate 0. 22 10 Tributyl phosphate 1 0. 23 23Triacetin 0. 40 23 Dirnethyl phthalate 0.33 13 Bis-(methoxyethyl)adipate 0.37 17 Trichloroethyl phosphate 0.33 10 Acetyl triethylcitrate.0. 39 13 Triethyl citrate 0.35 13 Butyl levulinate- 0. 31 13 Dimethyladipate 0. 34 18 Diethyl adipate 0. 38 13 Bis-(methoxyethyl) phthalate0.35 13 Adiponitrile 0.33 17 0. 35 13 1 0.37 33 Control (gel only) 0. 4133 Control (no antiabrasion layer) 0.43

1 Phase separation. Curl in diopters is defined as the reciprocal radiusof curvature in meters.

Additional coatings of antiabrasion layer were made and tested in thesame manner as for Table E as shown in the following table.

TABLE F Plasticizer:

Emulsion crack diameter at 10% RH, inches Triethyleneglycol diacetate0.39 Triethyleneglycol dipropionate 0.33 N-acetylmorphol-ine 0.39l-acetylpiperidine 0.40 N-methylformanilide 0.40 Diethylethoxyrnethylenemalonate 0.30 Alkylated phosphate ester (Vircol 189) 0.31 Polyethyleneglycol (600) dibenzoate 0.29 T etramethylene cyclic sulfone 0.37 Control(gel only) 0.42 40 Example IV Coatings similar to those of Example 111were placed in an oven at 125 F. overnight and then retested as inExample I for emulsion flexibility.

' TABLE G Plasticizer. 3 32 35 g g e Control (no antiabrasion layer)0.51 0.34

Tn'ethyl phosphate Tributyl phosphate 0.31 Triacetin 0.42 Dimethylphthalate 0.38 Bis-(methoxyet-hyl) adipate z- 0.35 Trichloroethylphosphate 0.38 Acetyl triethyl citrate 0.39 Triethyl critrate 0.40 Butyllevulinate 0.35 Dimethyl adipate 0.40 Diethyl adipate 0.38Bis-(methoxyethyl) phthalate 0.38 Adiponitrile 0.39 Diethyl succinate0.41 Dibutyl adipate (phase separation) 0.42 Triethylene glycoldiacetate Q. 0.33 Triethylene glycol dipropionate 0.46 N-acetylmorpholine 0.35 l-acetyl piperidine 0.35 Diethyl ethylphosphonate 0.38N-methylformanilide 0.40 Diethyl ethoxymethylene malonate 0.30 V-ircoll89-'allk=yl phosphate ester 0:31 Propylene carbonate 0.41 Polyethyleneglycol (600) dibenzoate 0.24 Tetramethylene cyclic sulfone 0.46

Control (gelatin only) 0.47

8 Example V It was discovered that plasticizers such as tributylphosphate could be conveniently incorporated into antiabrasion layers bynormal stirring in the presence of dispersed polyethyl acrylate in anaqueous gelatin solution. This is considered an important discoverybecause of the greater permanence of some of the less water solublematerials. Very insoluble materials, e.g., trioctyl phosphate or dibutylphthalate could not be completely incorporated into the dispersed vinylpolymer/gelatin sys= tern, however.

4 To 6000 ml. of a 5% by weight aqueous gelatin solution there wereadded:

270 ml. of a 3.3% by weight chrome alum solution, 3 g. of siliconelubricant,

915 g. of polyethyl acrylate dispersion containing 30% by weightpolyethyl acrylate and about 2.77% by weight amphoteric dispersingagent, prepared by emulsion polymerization as described in Procedure Aof assignees.

surfactants.

The pH was adjusted to pH 6.0-6.2 at F. Portions of 375 ml. each weremeasured 15 ml. of the plasticizers of plasticizer mixtures tabulatedbelow, dissolved in 60 ml. ethyl alcohol. Water was then added to eachportion to make a total of 600 ml. The solutions were then skim coatedat 1-0 ft./min. at 95 F. as antiabrasion layers over sections of thesixlayer color film of Example 11. The flexibility of these films wassuperior to those wherein the antiabrasion coating contained plasticizeralone and less water-soluble plasticizers, e.g., tributyl phosphate,were uniformly distributed in the coating. 2

In the above table the abbreviations have the following meaning:

PEA-:polyethyl acrylate dispersion TEP=triethyl phosphate TBP=tributylphosphate TA=triacetin DMP=dimethyl phthalate BMEA=bis-(methoxyethyl)adipate TCEP=trichlorethyl phosphate AT EC=acetyl triethyl citrateNumbers in parentheses following the abbreviations indicate relativeparts by volume.

and to each were added 9 Example VI TABLE 3' Additions to Emulsionantiabrasion layer: crack dia. inch Control (without abrasion layer)0.44 TEP+PEA 0.20 TBP-l-PEA 0.22 TA+PEA 0.29 DMP-l-PEA 0.27 BMEA-i-PEA0.27 TC-EP-i-PET 0.24 ATEC-l-PEA 0.35 DEEMM-i-PEA 0.35 Vircol 189phosphate ester-l-PEA 0.36 PEGDB-f-PEA 0.18 TEGDA-l-P-EA 0.24 DEEP+PEA0.20 TEC+PEA 0.33

The above table contains abbreviations as explained in Example V inaddition to the following new abbreviations:

DEEMM:diethylethoxymethylene malonate Vircol 189 phosphateester=ethylene oxide addition product of alkyl hydrogen phosphates asdescribed in U.S.P. 2,990,421 PEGDB=polyethyleneglycol dibenzoateprepared from polyethylene oxide having a molecular weight of 600TEGDA=triethyleneglycol diacetate DEEP=diethyl ethyl phosphonateTEC=triethyl citrate Example VII Experiments similar to Example V wereperformed employing, as before, 15 ml. plasticizer but with 100 ml.

ethanol to aid solution of the plasticizers, some of which proved tooinsoluble as will be seen.

*Trioctyl phosphate (/2 +TBP /2 +PEA 0.38 Trioctyl phosphate /s +PEGDB/3 +TBP /s)+PEA 0.37

The preceding table contains abbreviations as explained in Examples Vand VI. An asterisk is used where an oily surface was observed,indicating that one or more of the plasticizers were too insoluble toenter the polyethyl acrylate latex particles. Flexols 4G0, A26, and 3GHbehaved similarly in producing coatings with oily surfaces due toinsuflicient water solubility for use in the present invention.

Flexol 460 is polyethylene glycol di-(2-ethylhexoate) Flexol A26 isdi-(Z-ethylhexyl) adipate Flexol 3GH is triethyleneglycoldi-(Z-ethylbutyrate) Example VIII Emulsion additives such as dispersionof soft vinyl polymer and plasticizers can, in lengthy contact with aliquid photographic emulsion, produce undesired sensitometric effectsand coating disturbances. Accordingly, two multilayer color films weremade in which only polymeric compatible color couplers were present withthe usual gelatin and silver halide in the emulsion layers. One film, A,was made as a three-layer structure, i.e., emulsions containing cyan,magenta, and yellow color-formers were coated in that order onpolyethylene glycol terephthalate film base of 0.0045 inch thickness.The second film, B, was made similarly to A but in a laminated structurewith nonphotographic flexibilizing layers comprising gelatin, dispersedpolyethyl acrylate and plasticizer intercalated between the cyan andmagenta emulsions, and between the magenta and yellow emulsions, andcoated as an antiabrasion layer. Film A cracked at 0.67" while film Bcracked at 0.45", an obvious increase in flexibility.

The flexibilizing interlayer composition was prepared by combining 4000g. of a 5% aqueous gelatin solution with 180 ml. of a 3.3% chrome alumsolution at F. To this was added 610 g. of a polyethylacrylatedispersion (as described in Example V) along with saponin andt-CaHrr-QWCHzCHg) 10-011 surfactants. The pH was adjusted with 3 N NaOHsolution to 6.0 to 6.2 at 100 F. To this was added slowly with stirringa mixture of:

The flexibilizing interlayer was skim-coated at 100 F. and 10 ft./min.coating speed to give a gelatin coating weight of approximately 20milligrams per square decimeter.

The following examples illustrate the use of color formers other thanthose of the polyanionic type and the use of a thickplasticizer/gelatin/polyethyl acrylate latex abrasion layer which wasimproved flexibility characteristics and the additional advantages givenbelow.

Example IX A color film was prepared similarly to that described inExample H but with omission of the 6th layer, i.e., the outerblue-sensitive yellow-coupling emulsion layer. This film was then coatedin four separate sections as follows:

Emulsion Ooatmg Antiabrasion Layer Crack Dia. at 10% RH a 30 rng./dm.gelatin, 60 rug/Gm. PEA latex, 0.33 inch.

0.9 rngjdm. chrome alum plus surfactants. b Same as (a) plus 12 mg./drn.of triaeetin. 0.25 inch. 0 Saufie 1gas (a) plus 12 mg./dm. of tributylphos- 0.20 inch.

p a e. d Same as (a) plus 12 IngJdm. of dimethyl 0.24.

phthalate. e None 0.45.

Polyetbyl aerylate (dry weight) obtained from the aqueous dispersiondescribed in Example V.

The above coatings were cut into 10" and aged in contact with each otherfor at F. Coating (a), when processed, showed a mottled surface whichwas interpreted as due to tackiness of the anti-abrasion coat. Coatings(b), (c) and (d) showed x 35 mm. strips about 50 hours Example II butemploying containing plasticizer to 1 l very good gloss and freedom frommottle due, it is believed, to the surprising action of the plasticizersin preventing latex tackiness.

Coatings (a) through (e) were exposed through photographic step wedgesboth with and without a Wratten No. 29 red filter on the same 35 mm. xstrip. The exposed strips were then processed according to the procedureof five minutes first development at 75 F. for coating (e) and fiveminutes first development at 80 F. for coatings (a), (b), (c) and (d).It was observed that the gel. latex layer contributed wet-toughness tothe films as shown by the freedom of coatings (a) through (d) from hazeand reticulation compared with coating (e). Also, it was observed thatthe interimage development eifect to remove cyan dye from red areas wasincreased by the gel. latex outer layer. This could be seen in normaluse of a color reversal film as resulting in brighter and betterreproduction of reds.

Example X To demonstrate the usefulness of gel-latex overcoats for alltypes of integral couplers, e.g., polymeric, soaplike or dispersedlipophilic couplers, a 4-layer film similar to the first four coatedlayers of the 6-layer film of Example H was prepared. Also, thepolymeric cyan coupler of that film was replaced by a non-diffusingcoupler of the formula:

. S OsNa- Over a section of this 4-layer film was coated a layer asfollows:

After drying, this film was exposed and processed as in Example IX. Itwas observed that the original 4-layer film showed processing haze andedge-frilling of the emulsion when processed at 80 F. and that theover-coating prevented such defects and led to increased interimagedevelopments or masking efiects.

Other suitable color formers which can be substituted in similar amountfor the color former of Examples IX and X are described in U.S. patentslisted below-and described therein and in U.S. Patents 2,179,238 and2,186,849;

The advantages of the elements described in Examples IX and X are:

(a) The thick antiabrasion layer of gelatin plus polyethyl acrylatepromotes desirable interimage development or masking effects,

(b) The antiabrasion layers also permit higher temperature processingwithout occurrence of haze, reticulation and edge-frilling, and

(c) The addition of a high-boiling carbonyl groupthe gelatin polyethylacrylate antiabrasion layer prevents tackiness and lap-to-lap stickingof rolls of the resulting film elements.

The preferred photographic elements have a hydrophobic organic polymerfilm base that is dimensionally stable and is provided with a vinylidenechloride copolymer coating on each surface. Suitable polyester filrnbases are described in Alles et al. U.S. Patent 2,627,088.

In addition to preventing undesired sensitometric effects, the use of acombination of plasticizers and dispersed vinyl polymer in theinterlayer removes thickness 12 from the emulsion layers and adds to theseparator layers which may reduce interlayer color contamination andpossibly increase desirable interlayer development masking effects.

Elements made up of integral coupler emulsions obviously become moresusceptible to interlayer color contamination (particularly thecontamination due to migration of oxidized developer during the colordevelopment step) as the separator layers become thinner. It has beenfound that this color contamination can be efiectively reduced by theaddition of a competing coupler, e.g., a phenol that forms a solubleremovable dye on coupling (such as citrazinic acid). In particular, ithas been found that larger concentrations of sodium sulfite andcitrazinic acid are especially effective in combination with thepolymeric binder-color-formers in reducing interlayer colorcontamination caused by migration of oxidized developer and by migrationof color-former molecules. The films in which the vinyl polymerdispersion is removed from the emulsion and placed instead in theseparate layers tend to show reduced contamination due to increasedthickness of the separator layers. This, of course, does not increasethe over-all film thickness since the light-sensitive emulsion layersare made correspondingly thinner by the absence of these materials.

lthough this invention is particularly applicable to' negative andreversal color films which are designed for exposure in a camera, it isalso useful in other color films, which may have other than theconventional layer arrangements. The thin layers made possible by thisinvention can be used advantageously in negative, positive or reversalcolor films which may be for cine or still use,

in transparencies, prints for viewing by reflected light, intermediatefilms, etc.

The invention, moreover, is not limited to the specific light-sensitivematerial described in the above detailed examples. Various other simpleand mixed silver halides may be used as the light-sensitive materials inlike manner. Mixtures of silver bromides, chlorides, and/or iodides canbe made from mixtures of soluble salts of these halides in like manner.Other useful soluble halides include calcium bromide, potassium iodide,sodium and potassium chlorides and iodides, etc.

It is apparent from the foregoing that materials at the lower end of thesolubility range of this invention such as tributyl phosphate can bestirred into aqueous dispersion of soft vinyl polymers to obtain uniformcoatings without use of high-speed stirrers. However, it is found thataddition of a part of the emulsion gelatin to the aqueous dispersionprior to addition of plasticizer (in alcohol solution) is preferred tominimize any aggregation. This easily prepared mixture of tributylphosphate, aqueous polymer dispersion, and aqueous gelatin can be addedto any aqueous photographic emulsion. Such easily prepared mixtures ofplasticizers of water solubility from 0.5 to 10 g. per liter at roomtemperature, e.g., dimethyl phthalate, with soft polymer aqueousdispersion are particularly advantageous from the viewpoint ofresistance to loss by evaporation or water leaching compared with someof'the more Water soluble materials of the prior art, e.g.,triet'nyleneglycol diacetate, used alone.

This invention has been exemplified in terms of emulous similaritybetween color-formers of the type disclosed in the Chu et al.,application and the above nonpolymeric color-formers in that both haveionizable groups and weighting groups. Fundamental considerationsindicate that interaction and compatibility with gelatin occurs via saidionizable groups. Both types of couplers have such ionizable groups(carboxyl and/or sulfonate) and inherently contribute to brittleness inmultilayer films and, therefore, films containing both types ofcolor-formers may be significantly improved in a similar manner. 11-lustrative of the similarity of these two types of colorformers is thefact that the viscosity of an aqueous gelatin solution will be increasedconsiderably by the addition of an aqueous solution of either of thesetypes of color-formers. In contrast, no increase in viscosity of aqueousgelatin solutions is observed upon addition of that large class ofcolor-formers of the lipophilic or organic solvent-soluble type such asdisclosed in US Patents 2,108,602 and 2,126,337 and which are free ofcarboxyl or sulfonate groups.

The color-formers used in accordance with the invention are of highmolecular weight, essentially colorless and contain as an activedye-forming or color-former nucleus, a structure of the formula:

which is a general structure of the color'coupling nucleus in an enolform.

The foregoing nuclei are found in the reactive methylene dyeintermediates and in aromatic hydroxyl compounds and includes thereactive ethenol groups. These groups occur in phenols, naphthols,acylacetamides, cyanoacetyls, beta-ketoesters, pyrazolones,homophthalimides, coumaranones, indoxyls, thioindoxyls, and indazolones.Useful color-formers including those of this structure are described inUS. Patents 2,758,029, 2,927,019, 2,927,024, 2,997,388, 3,070,442, ineach of the patents listed therein and in the applications referred toabove.

Inert ingredients, e.g., pigments, colloidal silver, matting agents,etc. may be present in all of the element layers including the support.The element may also contain chemical sensitizers, optical sensitizers,coating aids, anti-foggants, non-halation dyes and pigments, brighteningagents as known to the art, etc.

With this invention it is possible to combine in a single multilayercolor photographic element the advantages of the integral color-formerstructure (ease of processing) with the advantages of superiorsharpness, definition, resolution, etc., normally associated with anon-integral color-former structure. The advantages of sharpness, etc.,are not inherent in the non-integral color-former structure exceptinasmuch as it has been impossible, prior to the present invention, toachieve, in a satisfactory mannet, the same thinness of emulsion layersin elements containing integral color-formers.

The outstanding advantage of this invention is the improvement inflexibility attained without sacrifice in the thinness or consequentloss in resolution and sharpness. Furthermore, the improvement inflexibility is retained even at very low relative humidities since theplasticizers of this invention do not require the presence ofatmospheric moisture to be effective. Other advantages of the elementsof this invention include improved toughness, particularly when wet,whereby the elements are able to undergo treatment in aqueous processingsolutions with excellent resistance to abrasion. With their goodflexibility, the emulsions have little tendency to crack, even at lowrelative humidity. Mounted transparencies, prepared from these elementsafter exposure and photographic processing, possess a unique superiorityin projection in that they do not pop due to the heat of the pro ectionlamp; thus the annoying requirement of changing the focus of theprojection lens is eliminated. The tendency of this film to curl at theedges has been reduced to a low level.

I claim:

1. A multicolor photographic element comprising a support bearing (1) aplurality of differentially sensitized silver halide emulsion layers,each layer being adapted to record an image from light in a difierentprimary color region of the visible spectrum and containing a colorformer having at least one nucleus capable of forming a dye selectedfrom the group consisting of quinoneimine, azomethine and azo dyes uponcolor coupling development of a silver salt image and gelatin, the colorformer in at least one of said layers being a gelatin-compatible,polyanionic vinyl addition polymer containing a plurality ofcolor-forming nuclei capable of forming an aforesaid dye, said emulsionlayers having an integral thickness, 6, of not more than 12.5 microns,and coated over said plurality of emulsion layers,

(2) a gelatin antiabrasion layer containing an organic plasticizerhaving an oxygen atom in its molecule which is doubly bonded to an atomselected from the group consisting of carbon, phosphorus and sulfur andbeing free from hydrogen atoms more acidic than pK =19 and having (a) aboiling point above 200 C., (b) -a melting point below 40 C., and (c) asolubility in water of at least 0.5 g. per liter at 25 C.

2. An element according to claim 1 wherein the gelatin antiabrasionlayer contains a vinyl addition polymer.

3. An element according to claim 1 wherein said support embodies amelt-cast, oriented polymer film that does not absorb the plasticizer,is transparent to visible light and there is an antihalation layerbetween the support and the emulsion layers.

4. An element according to claim 1 wherein said element comprises threesilver halide emulsion layers sensitive, respectively, to the blue,green and red regions of the spectrum.

5. An element according to claim 1 wherein said element comprises alight filter stratum which absorbs blue light and three light-sensitivesilver halide emulsion layers sensitive, respectively, to the blue,green and red regions of the spectrum.

6. A multicolor support bearing (1) a plurality of differentiallysensitized silver halide emulsion layers, each adapted to record imagesfrom light in a difierent primary color region of the visible spectrumand containing a water-permeable binder comprising gelatin and agelatin-compatible polyanionic color-forming vinyl addition polymeracting as a co-binder for said silver halide crystals and containing aplurality of color-forming nuclei capable of forming a dye selected fromthe group consisting of quinoneimine, azomethine and azo dyes uponcolor-coupling development of a silver salt image, said nuclei beingconnected to the polyvinyl chain through an amide group, said emulsionlayers having an integral thickness, 6, of not more than 12.5 micronsand coated over said plurality of emulsion layers (2) a gelatinantiabrasion layer containing an organic plasticizer having an oxygenatom in its molecule which is doubly bonded to an atom selected from thegroup consisting of carbon, phosphorus and sulfur and being free fromhydrogen atoms more acidic than pK =19 and having (a) a boiling pointabove 200 C., (b) a melting point below 40 C., and (c) a solubility inwater of at least 0.5 g. per liter at 25 C.

7. An element according to claim 6 wherein said support is a hydrophobicfilm base transparent to visible light photographic element comprising a5 55 and has an antihalation layer between the support and the emulsionlayers.

8. An element according to claim 6 wherein said element comprises threesilver halide emulsion layers sensitive, respectively, to the blue,green and red regions of the spectrum.

9. An element according to claim 6 wherein said element comprises alight filter stratum which absorbs blue light and three light-sensitivesilver halide emulsion layers sensitive, respectively, to the blue,green and red regions of the spectrum and each color former yields a dyewhich is complementary in color to the utilized sensitivity of therespective layer.

10. An element according to claim 6 wherein the gelatin antiabrasionlayer contains a vinyl addition polymer.

15 11. An element according to claim 10 wherein said vinyl additionpolymer is polyethyl acrylate.

References Cited 7 UNITED STATES PATENTS 2,633,423 3/1953 Bower et a1.96 87 3,178,288 4/1965 Orinik 96-87 3,211,552 10/1965 Chu et a1. 96-22OTHER REFERENCES Zelikman et al.: Making and Coating PhotographicEmulsions, The Focal Press, New York, pages 14-16 and 273-5 (1964).

J. TRAVIS BROWN, Primary Examiner,

